WinStars!

Celestia is a free real-time 3D space simulation, allowing unrestricted access to hundreds of thousands of stars.

KStars is a Desktop Planetarium for KDE. It provides an accurate graphical simulation of the night sky, from any location on Earth, at any date and time. The display includes upto 100 million stars, 13,000 deep-sky objects,all 8 planets, the Sun and Moon, and thousands of comets and asteroids.

StarCalc is the fastest professional astronomy planetarium & star mapping program for Windows 9x/ME/NT/2000/XP (StarCalc version for PocketPC is available). It illustrates star positions of any instance of the day observed from any geographic locations on the Earth. The star positions can be viewed and presented as images of hemispherical whole sky or any of the user defined sub-areas. These images can be zoomed at different scales, rotated, screen-captured and printed. Also, StarCalc has many other functions of calculation and showing of sky objects. »

Gaia Sky is a real-time, 3D, astronomy visualisation software that runs on Windows, Linux and OS X. It is developed in the framework of ESA's Gaia mission to chart about 1 billion stars of our Galaxy in the Gaia group of the Astronomisches Rechen-Institut (ZAH, Universität Heidelberg).

The WorldWide Telescope (WWT) is a Web 2.0 visualization software environment that enables your computer to function as a virtual telescope, bringing together imagery from the best ground and space-based telescopes in the world for a seamless exploration of the universe.

3D simulation of the Solar System and night sky - real time virtual orrery and observatory

Aciqra (uh-SEE-kruh) is a free and open source virtual sky map and planetarium which tracks and displays astronomical bodies including planets, nebulae and stars to an accuracy of a fraction of a degree for thousands of years into both the future and the past. It's software that generates a virtual sky so you'll know what's up in the real one.

Stellarium Mobile is a fully-featured planetarium for your phone. It shows a realistic night sky map in 3D, just like what you see with the naked eye, binoculars or a telescope.

Discover the universe with our downloadable atlas—the Digital Universe—where you can fly from the Sun out the edge of the observable universe.

SourceForge presents the Solar Model project. Solar Model is an open source application. SourceForge provides the world's largest selection of Open Source Software. The Solar Model is real time modeling of solar system. It allows user to navigate in space, to control time counting (speed-up time flow) and estimate movement of space bodies, bind camera to space objects (for example, from Moon on Earth in real time).